Refrigeration – Atmosphere and sorbent contacting type
Reexamination Certificate
1999-01-11
2001-03-27
McDermott, Corrine (Department: 3744)
Refrigeration
Atmosphere and sorbent contacting type
C062S094000
Reexamination Certificate
active
06205805
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is related to, and claims priority in, Japanese patent application Nos. Hei. 10-4884, 10-224448, and 10-313713, each being incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to vehicle air conditioning systems, and more particularly to a vehicle air conditioning system dehumidifier for dehumidifying ventilation air via a drying agent.
2. Description of the Related Art
In automotive vehicle air-conditioning systems, a passenger compartment is typically heated by utilizing warm water from an engine as a heat source. However, in recent years, as vehicle engines have become more efficient, the resulting temperature of the engine water has decreased, causing the heating capacity of the systems to often become insufficient.
To eliminate the above heating capacity deficiency, many conventional systems increase the percentage of inside air taken in to reduce the heating load. Specifically, an auxiliary door for mixing inside air with outside air has been added to a system inside/outside air switching box, or an inside/outside air 2-layer mode wherein only outside air is delivered to a defroster outlet side, and only inside air is delivered to a foot outlet side.
However, even in this inside/outside air 2-layer mode, when the percentage of inside air exceeds 50%, window fogging caused by increased humidity inside the passenger compartment occurs. Therefore, to reduce the heat load by increasing the percentage of re-circulated inside air and to simultaneously prevent window fogging, the atmosphere inside the passenger compartment must be dehumidified.
In Japanese Patent Application Laid-open No. H.9-156349, the present inventors have proposed dehumidifying the interior of the passenger compartment by means of a dehumidifier which utilizes a drying agent. However, because the amount of water adsorbed per unit of drying agent is small, a large overall amount of drying agent is necessary to obtain a required dehumidifying capacity. As a result, various problems arise, such as increased installation space required by the system as a whole due to the volume of the drying agent, increased airflow resistance presented by the drying agent, and increased energy required to regenerate the drying agent.
Also, a granular drying agent such as silica gel or zeolite is generally used as the drying agent. Thus, as water from passenger compartment air is adsorbed onto the drying agent, condensation of water vapor occurs and heat of condensation is produced. As a result, the temperature of the drying agent is raised by this heat of condensation, and the dehumidifying capacity of the drying agent consequently decreases.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to improve the dehumidifying capacity of a drying agent-based dehumidifier.
The present invention achieves the above object based on the fact that a water adsorption characteristic of the drying agent is greatly influenced by the relative humidity of the air passing over it, and is markedly improved by an increase in the relative humidity of that air. In the present invention, an air cooling unit, such as a heat exchanger, is disposed upstream of a drying unit housing the drying agent to cool air supplied from the inside of a compartment such as a motor vehicle passenger compartment. The air, having a high relative humidity after being cooled by the air cooling unit, is then dehumidified by the drying agent unit.
Consequently, the amount of water adsorbed per unit of drying agent can be greatly increased. As a result, the overall amount of drying agent required to obtain a dehumidifying capacity can be greatly reduced. Therefore, overall system size can be reduced due to the smaller amount of drying agent required, airflow resistance caused by the drying agent is reduced, and energy required for regenerating the drying agent is reduced.
According to another aspect of the present invention, a drying agent cooler for cooling the drying agent is provided to suppress a rise in temperature of the drying agent caused by heat of condensation of water vapor produced as the drying agent adsorbs water from the air. As a result, the water adsorbing capacity, that is, the dehumidifying capacity, of the drying agent can be increased.
According to another aspect of the invention, the drying agent cooler cools the drying agent unit with outside air. Because the outside air temperature is often around 0° C. during the winter, the low-temperature outside air can be utilized to effectively cool the drying agent, and thereby the construction of the dehumidifier can be simplified.
With this construction, in an air-conditioning system for a vehicle having an inside/outside air 2-layer flow mode, it is possible to reduce the heat load by increasing the proportion of re-circulated inside air and to prevent fogging of the windshield glass by dehumidified inside air and outside air being mixed together and blown out through the defroster outlet.
REFERENCES:
patent: 4180985 (1980-01-01), Northup, Jr.
patent: 4719761 (1988-01-01), Cromer
patent: 5423187 (1995-06-01), Fournier
patent: 5471852 (1995-12-01), Meckler
patent: 5509275 (1996-04-01), Bhatti et al.
patent: 5732562 (1998-03-01), Moratalla
patent: 5937667 (1999-08-01), Yoho
patent: 5950447 (1999-09-01), Maeda et al.
patent: 9-156349 (1997-06-01), None
Ban Koichi
Shirota Yuichi
Takahashi Koji
Denso Corporation
Harness Dickey & Pierce PLC
Jiang Chen-Wen
McDermott Corrine
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